The present invention is directed to improved heat exchange coils which avoid the collection of debris. More specifically, the improved heat exchange coils with tube rows having a boundary of some sort between adjacent tube rows are modified to avoid accumulating debris at that boundary.
Fin tube heat exchangers having a plurality of tubes running through a plurality of closely spaced plate fins are well known. When a fin tube heat exchanger is bent so that its area of operation extends to more than one side of a housing, the tube lengths in an outer row will vary with respect to the tube length in an inner row due to the increased radius of the bends traversed by the outer row. This can preclude a common plate fin from being used to engage both the tubes of the outer and inner rows at the same time. After a bend, distinct plate fins will often be used for the outer rows versus the inner rows, thus creating a boundary between the edges of the inner and outer plate fins. As airflow passes along the plate fins and around the tubes, any debris in the air will tend to accumulate at these boundary edges and potentially can block airflow through the heat exchanger, severely degrading its efficiency.
It is an object, feature and advantage of the present invention to solve the problems of the prior art.
It is an object, feature and advantage of the present invention to provide a fin tube heat exchanger with at least one bend in it where debris accumulation is minimized.
It is an object, feature and advantage of the present invention to provide a fin tube heat exchanger having a plurality of tube rows where the tube rows each include a first section in parallel, contacting relationship and a second section in diverging, non-contacting, relationship. It is a further object, feature and advantage of the present invention that the tube rows each include a bend where the radius of curvature of the bend in any particular tube row is distinctly different from the radius of curvature of a tube row bend in an adjacent tube row.
The present invention provides a fin tube heat exchanger. The heat exchanger comprises: a first tube row including a plurality of tubes, a planar slab portion and a first spread portion; and a second tube row including a second plurality of tubes, a planar slab portion and a second spread portion. The first and second tube rows include a slab portion respectively in contiguous parallel relation with the counterpart slab portion of the other tube row. The first and second spread sections are in diverging non-contacting relation with respect to each other.
The present invention also provides a fin tube heat exchanger. The fin tube heat exchanger comprises: a first tube row having a first portion, a second portion, and a third portion; and a second tube row having a fourth portion, a fifth portion and a sixth portion. The heat exchanger also comprises a first plate fin having a plurality of apertures in operative engagement with the tube rows of the first and fourth portion; a second plate fin having a plurality of apertures in engagement with the tube rows of the third portion; and a third plate fin having apertures in operative engagement with the tube rows of the sixth portion.
The present invention further provides a method of forming a heat exchanger. The method comprising the steps of: forming a first row of tubes in a first plane where each tube of the first row of tubes includes a first leg and a second leg; forming a second row of tubes in a second plane parallel to the first plane where each tube of the second tube row includes a first leg and a second leg; joining the respective first legs of the first and second tube rows with a common plate fin; providing second and third plate fins for the respective second legs of the first and second tube rows; and bending the second leg of the first tube row at a first angle such that the second leg of the first tube row is no longer in the first plane.